It is known from German Patent Application No. 2,853,178 to prepare diesters of dicarboxylic acids, the acid having two more carbon atoms than the unsaturated hydrocarbon used as a starting material by reacting an unsaturated hydrocarbon, carbon monoxide, an alcohol and an ester of nitrous acid in the presence of a compound of a metal of the platinum group and of a metal halide. Example 37 of this German Application shows that the desired diester was obtained in a relatively low yield, calculated on starting nitrite ester.
The Applicants have now found that by replacing this metal halide with a salt to be specified hereinafter a particularly high yield of the said diesters is obtained.